Search Results (623)

As a potential strategic resource of critical metals, deep-sea cobalt-rich crusts represent one of the most promising metal reservoirs within oceanic seamount systems, and their metallogenic mechanism constitutes a frontier topic in deep-sea geoscience research. This review focuses on the cobalt-rich crusts from the Magellan Seamount region in the northwestern Pacific and synthesizes existing geological, mineralogical, and geochemical studies to systematically elucidate their mineralization processes and metal enrichment mechanisms from a microstructural perspective, with particular emphasis on cobalt enrichment and its controlling factors. Based on published observations and experimental evidence, the formation of cobalt-rich crusts is divided into three stages: (1) Mn/Fe colloid formation—At the chemical interface between oxygen-rich bottom water and the oxygen minimum zone (OMZ), Mn²⁺ and Fe²⁺ are oxidized to form hydrated oxide colloids such as δ-MnO₂ and Fe(OH)₃. (2) Key metal adsorption—Colloidal particles adsorb metal ions such as Co²⁺, Ni²⁺, and Cu²⁺ through surface complexation and oxidation–substitution reactions, among which Co²⁺ is further oxidized to Co³⁺ and stably incorporated into MnO₆ octahedral vacancies. (3) Colloid deposition and mineralization—Mn–Fe colloids aggregate, dehydrate, and cement on the exposed seamount bedrock surface to form layered cobalt-rich crusts. This process is dominated by the Fe/Mn redox cycle, representing a continuous evolution from colloidal reactions to solid-phase mineral formation. Biological processes play a crucial catalytic role in the microstructural evolution of the crusts. Mn-oxidizing bacteria and extracellular polymeric substances (EPS) accelerate Mn oxidation, regulate mineral-oriented growth, and enhance particle cementation, thereby significantly improving the oxidation and adsorption efficiency of metal ions. Tectonic and paleoceanographic evolution, seamount topography, and the circulation of Antarctic Bottom Water jointly control the metallogenic environment and metal sources, while crystal defects, redox gradients, and biological activity collectively drive metal enrichment. This review establishes a conceptual framework of a multi-level metallogenic model linking macroscopic oceanic circulation and geological evolution with microscopic chemical and biological processes, providing a theoretical basis for the exploration, prediction, and sustainable development of potential cobalt-rich crust deposits. Full article

As energy exploration and development continue to advance into deep and ultradeep formations, systematic studies of rock mechanical properties face significant challenges due to high core acquisition costs and sample damage under extreme conditions. To overcome these challenges, high-precision, minimally invasive, or non-destructive testing methods are urgently needed. This study systematically characterizes the microstructural features and mechanical heterogeneity of deep carbonate rocks from the Shunbei area by integrating XRD, SEM-EDS, and nanoindentation techniques. The results show that these rocks are primarily composed of a continuous calcite phase, with quartz as the secondary phase occurring in regional aggregates embedded within the calcite matrix. The two phases commonly exhibit an intergrown texture, and mineral distribution displays notable spatial heterogeneity and sample-to-sample variation. Nanoindentation tests reveal that the quartz phase exhibits excellent mechanical stability, with elastic moduli ranging from 70.6 to 101.8 GPa and hardness values between 10.8 and 13.5 GPa. The data are tightly clustered, indicating structural homogeneity and strong resistance to deformation. In contrast, the calcite phase shows lower and more scattered mechanical parameters, with elastic moduli of 27.4~76.0 GPa and hardnesses of 0.7~2.3 GPa, reflecting pronounced microscale heterogeneity. Furthermore, a strong negative correlation exists between hardness and maximum indentation depth, further confirming the dominant influence of mineral composition on local mechanical response. Notably, despite similar mineralogical compositions among samples A13, A15, and A18, their micromechanical performance follows the order A15 > A18 > A13, indicating that subtle differences in diagenetic history, crystal development, and local stress conditions can significantly affect rock mechanical behavior. Full article

Gabal (G.) Suwayqat El-Arsha contains two distinct phases of granitoids: I-type granodiorite and A-type monzogranite. Both of them experienced intense fractional crystallization that affected plagioclase, alkali feldspar, quartz, and, to a lesser degree, ferromagnesian minerals. EnMAP hyperspectral data were used to discriminate between the different granitoid types through spectral analysis, using various techniques, including the Sequential Maximum Angle Convex Cone (SMACC) method. Granodiorite has high SiO₂ (68.21–71.44 wt%), Al₂O₃ (14.29–14.92 wt%), Fe₂O₃ (1.99–3.32 wt%), and CaO (2.34–3.87 wt%), whereas monzogranite has even higher SiO₂ (73.58–75.87 wt%) and K₂O (4.28–4.88 wt%). Both granodiorite and monzogranite exhibit calc-alkaline, peraluminous to metaluminous, and medium- to high-K characteristics, with attendant enrichment of light REE and LILE and depletion of heavy REE and HFSE. A negative Eu anomaly may indicate early plagioclase fractionation, especially in the monzogranite. The I-type granodiorite is likely derived from a high-K, mafic protolith that partially melted during lithospheric delamination, leading to severe fractional crystallization in the upper crust in a post-collisional environment. In contrast, the monzogranite exhibits A-type characteristics and was likely emplaced in an anorogenic setting. Both granites were affected by several episodes of hydrothermal alteration, resulting in silicification, kaolinitization, sericitization, and chloritization. The intrusions studied here exhibit key similarities with those in the Wadi El-Hima area, including tectonic setting, petrogenetic type, Neoproterozoic age (Stage I collisional: ca. 650–620 Ma; Stage II post-collisional: ca. 630–590 Ma), and mineralogical assemblages (notably two-mica granites). These correlations suggest that both suites form part of a regionally extensive batholith composed of I- and A-type granites, stretching from north of the Marsa Alam Road (Umm Salatit–Homrit Waggat) southward to at least Wadi El-Hima. Full article

The increasing demand for lithium in energy storage technologies has renewed interest in clay-type deposits as alternative resources to brines and hard rock ores. This study investigates the leaching behavior of a Mexican clay-type lithium ore through conventional, hot, and pressure leaching using sulfuric acid. Mineralogical characterization (XRD and SEM–EDS) revealed that montmorillonite (~56 wt.%) is the primary lithium-bearing phase. Conventional leaching with 1–8 M H₂SO₄ resulted in limited lithium dissolution (<30% after 24 h), whereas hot leaching at 80 °C increased extraction to ~39%. Pressure leaching with oxygen overpressure significantly enhanced lithium dissolution, achieving ~64% within 180 min under 8 M H₂SO₄ and 80 °C. Kinetic modeling using a pseudo-first-order model accurately reproduced the extraction profiles, yielding increasing rate constants and equilibrium conversions with temperature. The low activation energy (~12 kJ·mol⁻¹) indicates that lithium dissolution proceeds through weakly activated reaction–solution interactions rather than diffusion through a product layer. These findings provide a mechanistic basis for understanding lithium release from clay-hosted ores and highlight the importance of optimizing acid concentration, temperature, and oxygen availability to improve hydrometallurgical processing of clay-type lithium deposits. Full article

Rapid and reliable analytical methods are required to support quality control and decision-making in lithium-bearing mineral processing. In this study, the application of Fourier Transform Infrared (FTIR) spectroscopy combined with Partial Least Squares (PLS) chemometric modeling is evaluated for the simultaneous prediction of lithium oxide (Li₂O) and spodumene contents in pegmatitic samples. Two independent PLS models were developed using FTIR spectra preprocessed with first derivative and/or Standard Normal Variate (SNV). Spectral regions were selected based on the vibrational response of Al–O, Si–O, and OH⁻ groups, which are indirectly influenced by lithium-bearing phases. The spectral datasets were divided into calibration and independent external test sets, and model performance was assessed using statistical metrics and Principal Component Analysis (PCA). The Li₂O model achieved an R² of 0.9934 and an RMSEP of 0.185 in external validation, with a mean absolute error below 0.15%. The spodumene model achieved an R² of 0.9961, an RMSEP of 1.79, and a mean absolute error of 2.80%. These results demonstrate that the FTIR-PLS approach enables efficient quantitative estimation of lithium-bearing minerals, with reduced analytical time, good predictive accuracy, and suitability for application in process control and mineralogical sorting environments. PCA confirmed the statistical representativeness of the test sets, with no evidence of spectral extrapolation. Full article

The NASA Mars 2020 Mission Perseverance rover has conducted a four-Martian-year scientific campaign in the Jezero western fan, a typical fluvial–deltaic–lacustrine system on Mars. Equipped with the Planetary Instrument for X-ray Lithochemistry (PIXL) and SuperCam, the rover has collected high-resolution elemental data from abraded rock outcrops, providing a detailed geochemical and mineralogical characterization of key stratigraphic units. This work presents a systematic analysis of these targets, revealing distinct geochemical trends. Rocks from the delta front, upper fan, and margin units are enriched in Mg and Fe (e.g., mafic to ultramafic lithologies) and are depleted in Si, Al, Na, and Ca. These units share comparable mineral parageneses and exhibit pervasive alteration textures, in contrast to the more limited alteration observed in crater floor targets. Despite this, we also discussed insights derived from elemental data: (1) Low to medium chemical index of alteration (CIA) and modified index of alteration (MIA) values indicate limited silicate weathering. (2) Localized enrichments in Cl and Br suggest episodic mobilization of brines. (3) The presence of high-silica phases near the margin unit further points to hydrothermal processes. These observations suggest that sedimentation and diagenesis in the Jezero western delta were shaped by a complex interplay of fluvial, lacustrine, and localized hydrothermal processes. Full article

The construction sector is progressively prioritizing environmental norms owing to its substantial role in carbon emissions from clinker manufacture. Industrial waste materials are increasingly used as alternative constituents in cement-based systems, garnering interest as a sustainable strategy. Ceramic waste powder (CWP), produced in substantial quantities with enduring properties, offers a viable alternative. Nonetheless, its elevated water absorption presents issues, requiring modification procedures such as hydrophobization and the use of nanosilica to enhance performance. This study assessed CWP in both raw and modified forms (ground and hydrophobized) as a partial aggregate replacement in concrete. A silane-derived chemical was employed for hydrophobization, with varying amounts of nanosilica. Recent mortar testing encompassed setting time, flow, and density. Durability was evaluated using capillary water absorption, and flexural and compressive strengths were quantified at 2, 7, and 28 days. Mineralogical and microstructural investigations were conducted utilizing XRD and FTIR to monitor hydration phases and reaction processes. Results indicated that unmodified CWP containing up to 1% (wt) nanosilica enhanced mechanical strength; however, elevated nanosilica concentrations diminished early strength. Hydrophobized CWP samples demonstrated improved early strength with nanosilica levels up to 0.5% (wt), but strength diminished at elevated concentrations. Microstructural analysis confirmed reduced portlandite levels and increased C–S–H production, thereby validating the progress of hydration. The regulated and altered application of CWP with nanosilica can improve mechanical performance and durability while promoting ecological sustainability in cement-based systems. Full article

Sulfides are essential tracers for understanding the redox conditions, diffusion processes, and thermal mechanisms involved in the formation of ordinary chondrites. Their mineralogical and textural evolution provides valuable constraints on the metamorphic history of parent bodies. In this context, the Ksar El Goraane meteorite, which fell in Morocco in 2018 and is classified as an H5 ordinary chondrite, represents a particularly instructive case for investigating sulfur behavior during thermal metamorphism. Petrographic observations combined with geochemical data obtained by electron probe microanalysis (EPMA) and energy-dispersive X-ray spectroscopy (EDS) were used to characterize the main silicate and sulfide phases and to evaluate their degree of chemical equilibration. The compositions of olivine (Fa_18–20), Mg-Rich orthopyroxene, and sodic plagioclase (An_10–15) display limited analytical dispersion and well-recrystallized textures, confirming that Ksar El Goraane experienced an equilibrated metamorphic grade consistent with an H5 ordinary chondrite. The sulfide assemblage is dominated by troilite (FeS), iron-rich pyrrhotite (Fe_1−xS), and pentlandite ((Fe,Ni)₉S₈), with minor occurrences of pyrite (FeS₂). Textural relationships and chemical homogeneity observed in backscattered electron images and elemental maps indicate progressive re-equilibration during thermal metamorphism. Formation and transformation temperatures of the sulfide phases are inferred through comparison with experimental and empirical constraints reported in the literature. These results suggest early high-temperature crystallization of troilite, followed by sulfur depletion leading to pyrrhotite formation, subsequent low-temperature exsolution of pentlandite, and localized late-stage pyrite crystallization. Full article

The depletion of the mineral resource base is inevitable. Therefore, it is necessary to adapt and expand the resource base by incorporating non-traditional copper sources in production. Slag samples from the Balkhash Copper Smelting Plant (Kazakhstan) were analyzed for phase composition, microstructure, and metal distribution using X-ray diffraction (XRD), scanning electron microscopy (SEM), and chemical and granulometric methods. The slags are characterized by a fayalite structure with a high content of FeO (35–45%) and SiO₂ (25–35%). Sample composition was determined as 0.7–0.8% Cu, 0.39–0.43% Pb, 2.53% Zn, 0.075 g/t Au, and 2.6 g/t Ag. Mineralogical and granulometric analysis revealed a uniform distribution of iron and slag-forming components (SiO₂, Al₂O₃, etc.) across the fractions. In contrast, non-ferrous and precious metals concentrated in the fine classes. Laboratory tests confirmed that the fine dissemination of valuable components led to low efficiency in magnetic and gravity separation, necessitating specific preliminary slag preparation to improve recovery. Flotation tests showed improved recovery, yielding copper concentrates with 4.57% copper content when the material was crushed to 80–90% of the −0.074 mm class. The research creates a basis for the development of environmentally safe and resource-saving technologies and provides initial data for future recovery technologies. Full article

Quantitative mineralogy plays a vital role in exploration geology by defining mineral assemblages, identifying metal-bearing phases, and providing clues to optimize ore processing. In peraluminous rare-metal granites such as those at Beauvoir (France), mineral quantification is challenging, especially in altered facies where partial replacement complicates the estimation of muscovite and feldspars. The present study applies micro-X-ray fluorescence (micro-XRF) to quantify mineral assemblages of the Beauvoir granite. Modal abundances were compared with normative proportions derived from whole-rock geochemistry. In fresh facies with Li contents between 4000 and 6000 ppm, albite and quartz dominate (~40% and 25%), respectively, while lepidolite averages 20%–25%. During alteration to greisen, feldspars and lepidolite are partly replaced by muscovite, reducing lepidolite by up to threefold and increasing muscovite to ~30%. The obtained results demonstrate that micro-XRF provides a fast and reliable method for quantifying mineral distributions in rare-metal granites. Combined with complementary microscale techniques, quantitative mineralogy offers a powerful approach to characterize Li-bearing granites, assess alteration intensity, and improve predictions of ore quality and processability. Full article

The aim of this work is to study the correlations of the elemental composition in the “soil–grape–wine” chain to determine the regional origin of Chardonnay grapes and wine. Soil samples (n = 40) from five vineyards in the Anapa region, Russia, taken from eight different depths, grapes from these vineyards (n = 75), and wines obtained from these grapes (n = 5) were analyzed using inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry. The mineralogical composition of the soils was determined using thermal and X-ray phase analysis. The mineralogical composition of vineyard soils mainly consists of calcite, quartz, nontronite, vermiculite, and muscovite. According to spectrometric analysis, the distribution of both the total content and the mobile forms of elements in soil profiles turned out to be similar. The content of Na, Ca, and Sr increased with increasing sampling depth, while the content of Co, Cu, Fe, Ni, Mn, Pb, and Zn decreased. Regardless of the area of cultivation, the predominant elements in grapes are K, Ca, Na, and Mg. It is established that the elemental profiles of grapes and wine are correlated. At the same time, during the winemaking process, a decrease in the concentration of most elements (Al, Ba, Ca, Cu, K, Mg, Mn, Ni, Rb, Sr, Ti, and Zn) is observed. It has been shown that the vine is able to accumulate not only mobile but also less bioavailable forms of metals from the soil (Cu, Fe, K, Rb, Ti, and Zn), while the migration of Ca and Na remains low (<7%). Using discriminant analysis, a model of grape identification based on the concentrations of Al, Li, Mn, Na, Pb, and Rb was developed. This model demonstrated a high accuracy (100% for training and test datasets) in grape classification by region, confirming that the elemental “fingerprint” is a reliable marker of terroir. Full article

The paper focuses on the characteristics of fouling from copper production on the tube surface in a waste heat recovery boiler during the transfer of heat from the flash furnace process gas. The likely mechanism of deposit formation on the tubes is described, and the morphology and chemical composition of the bound deposit taken from the radiation zone of the waste heat recovery boiler are reviewed. In addition, the impact of the presence of bound and loose deposits on the tube’s surface on the increase in the deposit surface temperature and the decrease in the heat transferred at the inner side of the tube is evaluated. Changes in the chemical, mineralogical, and phase constitutions along the thickness of the build-up were established on the basis of XRF, SEM, and XRD quantitative analyses. The heat exchanger tube temperature distribution was computed with the finite element method using an axi-symmetrical solution of the heat conductivity equation. Computing was carried out for a clean tube surface as well as for a case with loose and bound deposits present on the surface, with thicknesses of 0.5 cm, 1 cm, and 2 cm. The boundary conditions at the deposit side varied. For loose deposits with a thickness of 0.5 cm, the decline in the heat transferred was similar to the values obtained for a bound deposit with a thickness of 2 cm. It was established that, for a deposit with a thickness of 20 mm, there was an approximately 80% decline in the energy transferred by the walls compared to the clean tube surface. This study represents a novel approach by integrating mineralogical and phase analyses with finite element modelling to comprehensively assess the impact of both bound and loose deposits on heat transfer efficiency in waste heat recovery boilers from copper production. Full article

The age of the first construction of the churches of Nuestra Señora de las Viñas (Quintanilla de las Viñas, Burgos), Santa María de Rute (Ventas Blancas, La Rioja), and San Juan Bautista (Barbadillo del Mercado, Burgos) of the northern Iberian Peninsula has been subject to debate for decades. Some scholars date the construction of the churches to the Visigothic period (6th and 7th centuries), while others attribute them to the early Middle Ages (9th and 10th centuries). To shed light on this controversy, the ¹⁴C dating of the binder fraction of mortars of the earliest construction phases was carried out. To determine the suitability of the mortars for ¹⁴C dating, the mineral composition of the binder was determined by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Samples were dated using ¹⁴C Accelerator Mass Spectrometry (AMS). Binder mineralogy precludes some samples from radiocarbon dating. Radiocarbon dating of the Nuestra Señora de las Viñas mortars yielded ages of 534–640 cal AD and 584–658 cal AD. Santa María de Rute yielded ages of 564–650 cal AD, corresponding to Visigothic ages. The San Juan Bautista sample yielded an age of 876–995 AD, although a mortar stratigraphically below results was not suitable for dating. Full article

The depletion of natural resources remains a major global challenge, emphasizing the need to develop sustainable processes that enable both metal recovery and waste recycling. This study investigates the leaching of valuable metals from lead smelting slag using methanesulfonic acid (MSA), a biodegradable and environmentally benign reagent. Batch experiments were performed under different MSA concentrations (0.35–1.4 M) and temperatures (22–80 °C). Metal dissolution increased nearly linearly with acid concentration up to 1 M, with maximum recoveries after 60 min of 85% Zn, 64% Pb, 75% Cu, and 68% Fe. Copper dissolution was governed by the oxidation of Cu₂S, while Fe leaching was affected by pH variations that promoted re-precipitation. Kinetic modeling indicated mixed chemical–diffusion control mechanisms, with activation energies of 22.6 kJ mol⁻¹ for Zn and 31–33 kJ mol⁻¹ for Pb, Cu, and Fe. Beyond efficient metal extraction, the process generated a leach residue with reduced concentrations of base metals and a mineralogical composition dominated by stable calcium-silicate phases, improving its potential suitability for reuse in construction or mining backfill applications. Overall, methanesulfonic acid proved to be an effective and sustainable lixiviant, combining high metal recovery with the generation of recyclable slag, thereby contributing to circular metallurgical practices. Full article

Copper slag, a by-product of copper ore and concentrate smelting, is rich in non-ferrous metals; therefore, it has been considered a valuable raw material in recent years. This study aimed to compare the extraction of zinc, copper, and cobalt from two types of copper slag from a dump located near the village of Eliseyna, Bulgaria, which differ in mineralogical composition and chemical content, using indirect bioleaching with a spent medium of Aspergillus niger and Penicillium ochrochloron. Chemical leaching with sulphuric acid revealed that zinc and cobalt existed mainly as an acidic-soluble phase in both types of copper slag. In contrast, it contained 50–75% of the total copper content. Each fungal species was cultivated for one week, and the biomass and the spent medium were separated a week later. Owing to the production of a higher concentration of citric acid, A. niger facilitated more efficient base metal recovery. However, their effective recovery from the acidic-soluble phase required leaching at a 5% pulp density and supplementing the spent medium with sulphuric acid. The temperature played a secondary role. Conclusions: Non-ferrous metal extraction from copper slag exposed to weathering using a spent medium supplemented with sulphuric acid was achieved under milder leaching conditions and with better selectivity. In contrast, slag unaffected by weathering behaved as a refractory due to the worsened results of base metal extraction under similar experimental conditions. Full article